ADO.NETDATABASES IN VISUAL BASIC.NET

ADO .NET

ADO.NET is an OO framework that allows you to interact with DBs

Can use ADO.NET through code, or by using bounded controls

ADO.NET extremely flexible and efficient

ADO.NET

Previously applications would talk to Database using SQL

The application would be constantly connected to the DB

We still use SQL but the data is disconnected

It will connect to a database server when it needs to run a query and then disconnects immediately

ADO.NET still provides the connection oriented traditional approach.

Traditional Data Access Architecture

1. Makes a Connection 2. Pass some query to DB and reads

result3. Pass another query to DB and reads

result4. Disconnects from DB System

ADO.NET Disconnected Model1. Make a connection2. Pass query and gets back result3. Disconnects4. Makes connection again5. Passes another query and gets

result6. Disconnects from the DB

ADO.NET

Keeps a local virtual copy of the database in your application

All of the generic classes for data access are stored in the System.Data Namespace.

ADO.NET

ADO.NET uses managed providers to connect to databases

Managed providers allow fast data streams from databases

Deals with security such as database locks, passwords etc.,

Main Components of ADO.NETObject Description

Connection Creates a connection to the data source

Command Provides access to commands that can be executed against the data source

DataAdapter Serves as an ambassador between your dataset and datasource, maps instructions between the two

DataSet Provides an in-memory representation of your data source

DataReader Read-Only forward stream containing your data

Advantages

Interoperability Data is transported as XML Can be read by anyone on any platform

Scalability Client Server model is gone ADO promotes the use of disconnected

datasets Productivity

Quicker Less Bugs

Advantages Cont’d

Performance Disconnected datasets Database Server is no longer a bottleneck Performance boost Concurrency Database not locked out all the time

Using ADO.NET in Code

1. Set up your objects2. Connect to DB using connection

object3. Set up the data adapter 4. Copy data from data adapter to

Dataset

USING ADO.NET WITH ACCESS DB

Connecting to a DB in Code

A Simple DB Application

Code Cont’d

Code Cont’d

Code Cont’d

Doing it In Code

An access Database Table It will be represented in our DataSet as

a Table The first table is given an index of 0 The first row in the table has an index

value of 0 also The first column has a value of 0

Code Cont’d

The Code

Set up the objects

The Code

Set up the objects

The Code

Set up the objects

The Code

Set up the objects

The Code

Set up the objects

The Code

Fill the DataSet using the DataAdapter

The Code – Displaying the DataSet Contents

Point a textbox to a row and column of the dataset Table

Point a DataGrid control at a DataSet

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The Code: Counting the Number of Rows

Point a textbox to a row and column of the dataset Table

Point a DataGrid control at a DataSet

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Customising the Generic Code

Set Up the Objects

The Form Load Code

The UpdateTextBoxes Sub Procedure

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